Pier for offshore drilling rigs



July 12, 1949.

Filed Sept. 19, 1947 4 Sheets-Sheet l INVENTORQ AALE/V 5. HACAf/T July12, 1949. A KET 2,475,888

PIER FOR' OFFSHORE DRILLING RIGS Filed Sept. 19, 1947 4 Sheets-Sheet 2E5 3. Fry 2 Ill llll

A ll lll II In #14 1 I I INVENTOR.

July 12, 1949. A. s. HACKETT PIER FOR OFFSHORE DRILLING R IGS 4Sheets-Sheet 3 Filed Sept. 19, 1947 INVENTOR.

:ALLEN 5. HAC'KETT July 12, 1949. A. s. HACKETT PIER FOR OFFSHOREDRILLING RIGS Filed Sept. 19, 1947- 4 Sheets-Sheet 4 INVENTORY AZZf/V 5.HAM 77 BY 7 2mm, q/

Patented July 12, 1949 UNITED STATES PATENT OFFICE PIER FOR OFFSHOREDRILLING mos Allen S. Hackett, New Orleans, La. Application September19, 1947, Serial No. 775,647

8 Claims.

The present invention relates to so-calied oilshore drilling; i. e., theoperation of drilling for oil in areas where the ground surface issubmerged, such as the localities defined geologically as theContinental Shelf and particularly in the Gulf of Mexico and contiguousbayous where the bottoms are composed of an overburden of alluvialdeposits, muck and soft sand.

My invention has for its object to provide a pier or caisson which iscapable of being sunk in the soft floor of a sea to whatever depth maybe required to reach a firm underlying stratum and may be built upwardlyin sections to any desired height for supporting a load above tide leveland storm wave height of the water.

Another object of my invention is to provide a pier in the form of acylindrical caisson built with double exterior walls between which arespiral inclines for displacing the overburden of the sea floor as thepier is rotated.

A still further object of my invention is to provide a pier ofcylindrical hollow form of substantial diameter capable of being rotatedin situ by two or more surface craft or tug boats and provided aroundits periphery with means for dislodging material at the sea bottomaround a central core to the required depth to engage an underlyingsupporting stratum.

To these and other ends my invention comprises further improvements andadvantages as 30 will be further described in the accompanyingspecification, the novel features thereof being set forth in theappended claims.

In the drawings:

Figure 1 is a side elevation of a pier or caisson embodying myinvention. I

Figure 2 is a top plan view thereof.

Figure 3 is a vertical central sectional view of the structure taken onthe line 3--3 of Fig. 2

shown before commencement of the seating op- 40 eration.

Figure 4 is a similar view showing the structure when seated.

Figure 5 is a perspective view showing the upper end of a pier orcaisson and the method of rotating it by surface craft to cause itslower end to become embedded in the sea bottom.

' capable of being built in sections to any desired Figure 6 is a planview illustrating one of theinterior reinforcing braces for the innercylinder. Figure 7 is an enlarged fragmentary view of the movable pistonhead which overlies the central core formed by the descent of the pier.

Figure Bis an elevational view showing several of the piers assembled asa support for a plat- 2 form carrying a conventional derrick or drillingrig.

Similar reference numerals, in the several figures, indicate similarparts.

In drilling for oil and/or gas in offshore locations in certainlocalities, such as those bordering the Gulf of Mexico, in the bayouregions of Louisiana, as well as in the bayous themselves, considerabledifiiculty is experienced in obtaining a sufliciently firm foundation tosupport the necessary drilling rig and its appurtenances. This is due tothe heavy overburden or silt or unsolidified deposit of earthy matterwhich is often of such thickness that it is difilcult to get a footingfor an underpinning of the usual long piling to support a surfaceplatform on which to erect a derrick, draw works, power plant and easingrack together with the necessary accommodations for the workmen andfortheir handling of the customary tools, particularly the drill stem usedin rotary drilling operations. This fundamental dimculty in obtaining astable platform I am able to overcome by providing a new form of, pilecapable of being sunk to a firm foundation, through any depth ofalluvial deposit, or soft sand, and by using a plurality of them toprovide a platform support of any required area and capable ofsustaining a gross weight of many tons without shifting. To the aboveends my invention embodies a pile unit characterized by a constructionwhich enables it to be set in operative position by rotary action asdistinguished from the customary method of sinking piles used forunderpinning by driving them downwardly.

In carrying out my invention I construct my new form of pile in sectionssomewhat in the nature of a caisson in that it is a hollow shell length.This shell has a large diameter in proportion to its length and inordinary offshore operations in the Gulf of Mexico an overall diameterof 30 feet is considered proper. The shell comprises an inner cylinderIll and an outer concentric cylinder ll sufliciently larger to provide asubstantial intervening space which may be in the neighborhood of fouror live feet in which there are erected two spiral ramps i2 and I3 whichare continuous from diametrically opposite points at the bottom of theshell to its top. These ramps constitute enormous screw threads formedon a pitch which enables the soft mud to be easily displaced or forcedupwardly thereon. The inside cylinder is impervious but the outercylinder is provided with openings or fenestra l4 arranged in spiralfashion to allow the escape of more or less of the displaced mud.

Surrounding the lower end of the outer cylinder II is an outwardlyflaring flange or skirt IS the rim of which extends slightly beyond theleading edges of the two ramps and serves to direct ocean bottom mudinwardly onto said ramps and further toward the center of the shell.

Within the inner cylinder in is a piston head IS the guiding side wallsI! of which extend upwardly and carry a ring l8 provided with an annularrecess for the accommodation of packing i9. For holding the latter incontact with the inner periphery of the cylinder I I providesemicircular packing rings 20 which may be adjusted as circumstancesrequire by pressure screws 2| (see Fig. 7). This piston head isinitially located at the bottom of the shell, as shown in Fig. 3, and ispushed upward as the shell descends, by the core or central column ofmud 22, as shown in Fig. 4. By providing a closure over said core andshutting off the free flow of water into the inner cylinder at a pointabove the ocean bed the core is caused to aid both in maintaining theshell erect and preventing its lower end from being shifted either bywave action or otherwise.

At suitable intervals above the uppermost position of the piston,especially when the shell is required to be built up of a number ofsuperposed sections to reach a desired height above tide level I providetherein cross bracing. The latter I make in the form of spiderscomprising a number of arms 30 radiating from an apertured center block3| on which are carried segmental shoes 32 which bear against the innerside of the inner cylinder. In order to provide a simple means ofadjusting the shoes I form the sections of the arms on which they arecarried as separate pieces and employ threaded turnbuckle collars 33 forconnecting the two sections of each arm.

As shown in the several illustrations I provide at the top of eachsection of the shell an outer collar 40 on the outer cylinder one halfof which I extends above the upper end thereof and serves to seat thelower end of the succeeding section. The collar in the first instance issecured permanently in place by a row of rivets 4| and when the nextcylinder is placed therein it is firmly united thereto by a second rowof rivets 42. In practice the use of two or more superposed sections isdetermined by two factors, one the depth of the water, at the pointwhere the shell is to be placed and the other the thickness of thepenetratable depth of the underlying bed in which it may be possible toscrew the lower end of the shell. In starting the operation it isdesirable to use a single section or such number thereof as will locatethe top of the shell as close to the water level as may be andsubsequently connect in place additional sectional lengths as may .berequired. For this reason it is recommended that the uppermost sectionsbe of less length than the preceding ones.

The modus operandi of sinking the shell consists in placing it in anupright position at the site where its weight will cause its lower endto sink into the mud bottom sufficiently to stabilize or center it whenpower is applied to its upper end to rotate the shell bodily. Thislatter operation may be effected inany appropriate manher. The diameterof the shell which provides a large leverage contributes to thesuccessful employment of two or more tugs 50-5! connected by two lines5253 to eye bolts 54 on opposite sides of the uppermost section of theshell as shown in Fig. 5. The tow lines may be wrapped around the shelland extend in opposite directions from the two sides of the shell andthe tugs move outwardly along straight lines to impart rotary movementto the shell as the lines unwind. or if the lines are connected to theeyebolts the tugs may steam in a circular path concentric with the shellas shown in Fig. 5.

The rotational movement of the shell causes the ramps l3--l4 to dig intothe mud, or other soft strata, that may be encountered and that which isdisplaced, to accommodate the thickness of the metal, is allowed toescape or is forced laterally out'of the window openings I4. When thelower end of the shell reaches an impenetrable underlying stratum or hasbeen screwed down in the ocean bottom mud to a stop point beyond whichit becomes impossible to further rotate the shell it will be found thatthe shell has become solidly anchored, a fact which I attribute to theincreasing density of the mud and to the load it adds to the shell as itrests on the ramps, or screw threads, as well as to the contained core22.

While it is not necessary to continue the ramps in those sections of theshell lying above the ocean bed there is a convenience aflorded in sodoing since they serve as spacing connections between the inner andouter cylinders, on the order of stay bolts. In addition to this,however, with sections thus made they become interchangeable in that anyone of them may be used as a bottom section, irrespective of whether ornot, in such instances, the bottom skirt flange I5 is first applied toits lower end.

It will be readily understood that any number of the aforedescribedshells may be set up and grouped in any desired pattern to provide asupport for a platform 60, as shown in Fig. 8, indicative of a suitablesupport for a drilling rig indicated generally by the derrick 6|.

I claim:

1. A foundation pier for offshore drilling rigs comprising verticallyextending spaced inner and outer cylinders, a spiral ramp located insaid space, the outer cylinder having openings to permit the escape ofmaterial fed upwardly on the ramp as the cylinders are rotated.

2. A foundation pier for offshore drilling rigs comprising verticallyextending inner and outer concentric cylinders spaced apart, and tworamps forming parallel spirals located in said space and leadingupwardly from the lower ends of the cylinders for feeding subaqueousmaterial upwardly when the cylinders are revolved.

3. A foundation pier for ofishore drilling rigs comprisin inner andouter concentric cylinders spaced apart, and each open at their ends,ramps spiralling upward from the lower ends of the cylinders located inthe space between them and connecting said cylinders, the outer cylinderbeing provided with apertures spaced along the ramps, forming exitopenings for the escape of material thereon.

4. A foundation pier for offshore drilling rigs having an underwater andsubaqueous open lower end composed of spaced outer and inner cylindersand a ramp located in said space, the inner cylinder forming areceptacle for an ocean bed core and the outer cylinder and ramp forminga surrounding cutter for such material, said outer cylinder beingprovided with apertures arrangedalong the ramp and forming exits formaterial displaced by the ramp. the pier having an upper end extendingabove the water line by acmeee means of which said pier may be rotatedto sink its lower end in a subaqueous bed.

5. A foundation pier composed of inner and outer concentric cylindersspaced apart having open lower ends, a ramp spirally located in saidspace and leading upwardly from the lower ends of the cylinders, apiston head located at the bottom of the inner cylinder and movableupwardly under pressure of the core of material formed therein by reasonof the sinking of the pier.

6. A subaqueous foundation pier composed of spaced inner and outerconcentric cylinders openat their ends'composed of a plurality of likeinterchangeable sections superposed and rigidly connected together, aramp spiralling upward from the bottom of the cylinders and located inthe space between them, the outer cylinder having apertures spaced alongthe ramp, and a piston initially positioned at the lower end of theinner cylinder and movable upwardly therein under pressure as the piersinks and its lower end penetrates subaqueous material.

'7. A subaqueous foundation pier composed of spaced inner and. outerconcentric cylinders open at their ends composed of a plurality of likeinterchangeable sections supe p sed and rigidly connected together, a.ramp spiralling upward under water bed and having an upper endprojecting above the water line and second sinking the pile by rotatingit by means of a plurality of tugs steaming in a circular path aroundthe pile and connected to its upper end by flexible connections.

ALLEN S. HACKEIT..

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,501,706 Zubiria July 15, 19242,129,978 Yokoyama Sept. 13, 1938

